1. Field of the Invention
The present invention relates to airfoil performance. More specifically, the present invention relates to a method and an apparatus for automatically generating airfoil performance tables.
2. Related Art
In order to analyze the performance of an airfoil, airfoil analysis codes typically make extensive use of two-dimensional performance data. This two-dimensional airfoil performance data is typically stored in “C81 airfoil performance tables.” C81 tables are text files, which list the lift coefficient, drag coefficient and pitching moment coefficient as functions of angle of attack for a range of Mach numbers. Typically, the angle of attack spans angles from −180° to 180°, while the Mach number ranges from 0.0 to 1.0. In the past, tables were created from experimental data and researchers' best estimates as to how the airfoil should perform at certain flow conditions.
Due to the high cost of wind tunnel tests, only a handful of airfoil sections have been tested over the entire 360° angle of attack and Mach number ranges. These data are often faired into tables being created for new geometries as a way of filling in the gaps where experimental data is not available. Due to this process, it is difficult to ensure any level of consistency in existing tabular data as far as compressibility effects, viscous effects or even sectional geometries are concerned.
C81 tables are thus often incomplete, and often contain inconsistencies in reference Reynolds numbers, airfoil geometry, and the like. These problems make relying on C81 tables for design tradeoff studies and geometry modifications problematic at best.
Hence, what is needed is a method and an apparatus for automatically generating airfoil performance tables without the problems described above.